How to use [Microsoft.Win32.RegistryValueKind]::TryParse-CodePudding

I can't seem to get [Microsoft.Win32.RegistryValueKind]::TryParse to work properly. Each solution I try always returns Cannot find an overload for "TryParse" and the argument count: "2". (or "3") despite the fact it shows the following.

PS C:\Windows\system32> [Microsoft.Win32.RegistryValueKind]::TryParse

OverloadDefinitions                                                                                                                          
-------------------                                                                                                                          
static bool TryParse[TEnum](string value, [ref] TEnum result)                                                                                
static bool TryParse[TEnum](string value, bool ignoreCase, [ref] TEnum result)

In my experience any of the following should normally work just fine.

[Microsoft.Win32.RegistryValueKind]::TryParse('dword',[ref]$Null)
[Microsoft.Win32.RegistryValueKind]::TryParse('dword',$true,[ref]$Null)

In the meantime I can just cast the string as [Microsoft.Win32.RegistryValueKind] but I am curious as to what I am doing wrong.

CodePudding user response：

The [Microsoft.Win32.RegistryValueKind]::TryParse() method by itself will return either $true or $false, depending if the parsing succeeded or not.

The first parameter is the string value you want parsed converted to one of the RegistryValueKind enum types.
The last parameter is the variable containing the RegistryValueKind type of choice.
The method then tries to convert the given string value to that registry kind.
Optionally, there is an overload with a second parameter in between you can set to $true to have it work case-insensitive on the given string value.

example:

[Microsoft.Win32.RegistryValueKind]::TryParse('12345', [ref][Microsoft.Win32.RegistryValueKind]::DWord)

returns True because '12345' can be converted to integer DWord valuekind.

You can also read back the parsed value like this

$result = [Microsoft.Win32.RegistryValueKind]::DWord   # 4
if ([Microsoft.Win32.RegistryValueKind]::TryParse('12345', [ref]$result)) {
    Write-Host "The value can be stored as $result (DWord)"
}

Anyway, if your intention is to read registry values and try to determine if the RegistryKind of that entry is correct, I think the RegistryKey.GetValueKind() method would be easier to use

CodePudding user response：

TryParse is actually implemented by System.Enum, and is a generic method. It returns a bool whether the parse succeeded, and the second parameter is an out with the actual parse result.

You have a number of issues if you want to use TryParse.

Firstly, you cannot call a generic method directly in Powershell unless you are using PS 7.3 or above

[System.Enum]::TryParse<Microsoft.Win32.RegistryValueKind>('DWord', [ref]$prm)

For versions of Powershell which use .Net Core or .Net 5 (I don't if there are any), you could also use the non-generic version of TryParse

[System.Enum]::TryParse([Microsoft.Win32.RegistryValueKind], 'DWord', [ref]$prm)

Be that as it may, in earlier versions you need to use reflection.

$arrParams =  @('DWord', $null)

$method = ([System.Enum].GetMethods() | where {($_.Name -eq "TryParse") -and ($_.GetParameters().Length -eq 2) })[0].MakeGenericMethod(@([Microsoft.Win32.RegistryValueKind]))

$method.Invoke($null, $arrParams);

$arrParams[1]

Note that the string parameter is case-sensitive, and therefore must be 'DWord'